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Long multiplication – column method

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Presentation on theme: "Long multiplication – column method"— Presentation transcript:

1 Long multiplication – column method
Example 87 × 25 To multiply by 25, multiply by 5, then by 20 and add the answers 8 7 2 5 × Multiplying by 5 5 × 7 = 35 5 × 8 = 40 = 43 4 3 5 3 To multiply by 20, put the 0 in the units column, then multiply by 2 1 7 4 1 2 1 7 5 2 × 7 = 14 2 × 8 = 16 = 17 Then add 87 × 25 = 2175

2 Long multiplication – column method
Example 216 × 34 To multiply by 34, multiply by 4, then by 30 and add the answers 2 1 6 3 4 × Multiplying by 4 4 × 6 = 24 4 × 1 = 4 4 + 2 = 6 8 6 4 2 4 × 2 = 8 6 4 8 1 To multiply by 30, put the 0 in the units column, then multiply by 3 7 3 1 4 1 4 3 × 6 = 18 3 × 1 = 3 3 + 1 = 4 3 × 2 = 6 216 × 34 = 7344 Then add

3 Long multiplication – grid method
Example 87 × 25 Draw a 2 by 2 grid Separate the tens and units. Then multiply. Add across then down. 20 × 7 20 × 80 80 7 1600 140 20 5 + 1740 400 35 435 5 × 80 5 × 7 2 1 7 5 87 × 25 = 2175

4 Long multiplication – grid method
Example 216 × 34 Draw a 3 by 2 grid Separate the hundreds, tens and units. Multiply. Add across then down. 30 × 10 30 × 200 30 × 6 200 10 6 30 4 6000 300 180 + 6480 800 40 24 864 4 × 200 4 × 10 4 × 6 7 3 1 4 1 4 216 × 34 = 7344

5 Try these on paper in your preferred method
1) 46 × 21 7) × 25 2) 83 × 45 8) × 71 3) 97 × 68 9) × 64 4) 65 × 39 10) × 53 5) 87 × 24 11) × 27 6) 56 × 48 12) × 49


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